Objective: To examine the relationships between TNF-alpha, obesity, and insulin resistance among prepubescent children.
Design: Cross-sectional study.
Setting and subjects: Data were collected from 112 nondiabetic Latino schoolchildren from public schools in three South Florida communities. Of the enrolled participants, 43.8% were obese (BMI 95th percentile) and 51.8% presented with a family history of type 2 diabetes mellitus (T2DM). With one exception, all demonstrated normal glucose tolerance.
Interventions: Plasma TNF-alpha levels were determined with enzyme-linked immunosorbance assay (ELISA). Homeostasis model assessment (HOMA-IR) was calculated as an index of insulin resistance. Mean levels of TNF-alpha among obese vs nonobese children were compared with a one-way analysis of variance with two groups, and the association between TNF-alpha and HOMA-IR was assessed with a Pearson's correlation.
Results: Higher circulating TNF-alpha levels were revealed among nonobese vs obese children. Nonobese girls demonstrated higher TNF-alpha levels than obese girls, whereas there were no significant differences for boys. There were no significant differences after stratifying for family history of T2DM. There was a modest relationship between increased TNF-alpha levels and decreased insulin resistance.
Conclusions: The observed elevated circulating TNF-alpha concentrations among leaner participants may reflect an inflammatory process that has been associated with higher levels of physical fitness in both adults and prepubescent children. This effect may remain stronger for prepubescent girls, and the mechanism may be attenuated by the hormonal changes that occur with the onset of puberty.